Karel Petr

Karel Petr ( 14 June 1868, Zbyslav, Austria-Hungary – 14 February 1950, Prague, Czechoslovakia) was a Czech mathematician. He was one of the most renowned Czech mathematicians of the first half of the 20th century.

Biography
Petr is known for the Petr–Douglas–Neumann theorem in plane geometry, which he proved in 1905 (in Czech) and in 1908 (in German). It was independently rediscovered by Jesse Douglas in 1940 and by B H Neumann in 1941.

Eduard Čech was a doctoral student of Petr at Charles University in Prague. Petr's doctoral students also included Bohumil Bydžovský and Václav Hlavatý.